Hook Video: Battle of Kruger

Evolution – The relative change of the gene pool (alleles) of a population that occurs over generations.

Introducing Evolution

The kittens in this litter have different fur colour and patterns, partly because eachkitten inherited a different combination of alleles from its parents.

Variation Within SpeciesVariations – structural, functional, or physiological

differences between individuals within a species.

• Variations are created by the different combinations of genetic information (alleles) that offspring inherit from their parents.

What is the ultimate source of genetic variation? Mutation – a permanent change in the genetic sequence (DNA) of an organism and the only source of new genetic variation (new alleles). This is only true if the mutation alters the DNA in a gamete, so that DNA can be passed on to offspring.

Mutations can occur spontaneously during DNA replication (S-phase), or caused by mutagens (eg. UV-radiation)

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Variations & Adaptations

Adaptations – structural, behavioural, or physiological processes that help an organism survive and reproduce in a particular environment.

Camouflageallows this stickinsect (Eurycnemagoliath) to blendin with itsenvironment andavoid beingeaten bypredators.

Many owls suchas this barn owl(Tyto alba) cansneak up on theirprey because ofanotheradaptation: fluffyfeathers maketheir flight quitesilent.

Mating Rituals: Dancing and/or Singing – Behavioural adaptation

Types of Adaptations:

Hibernation – Physiological adaptation

Hibernation allows ground squirrels to survive in climates with harsh winters. They reduce their metabolism in order to conserve energy.

Mimicry – Structural adaptation

Mimicry - an adaptation in which harmless species physically resemble a harmful species. Predators avoid the harmless species as much as they do the harmful one.

The viceroy butterfly (top) has coloration similar to the bad-tasting species monarch butterfly (bottom).

Hornet Moth:- looks like a hornet, but is completely harmless.

Io Moth (Automeris io):– spread their wings to reveal a startling eyespot pattern, used to deter predators.

Infer.......How could the camouflage of individual stick insects help the survival of a population of stick insects?

• Organisms constantly face environmental challenges that limit their ability to survive.

• Severe weather, famine, and competition for food, space and mates are all challenges to survival.

• Environmental conditions determine whether a variation in an individual has a positive, negative, and/or neutral effect.

• Individuals with a helpful variation are more likely to survive and have a higher chance of passing on the genetic information (alleles)

• A characteristic may not give an individual a particular advantage now but may become critical for survival later as the environment changes.

Selective Advantage – a genetic advantage that favours an organism’s chance of survival and reproduction, usually in a changing environment.

Eg. Antibiotic-Resistant Bacteria

E.g. When a human was born with a thumb

E.g. Drought resistant frutis